Impact of the degree of peri-interventional platelet inhibition after loading with clopidogrel on early clinical outcome of elective coronary stent placement

J Am Coll Cardiol. 2006 Nov 7;48(9):1742-50. doi: 10.1016/j.jacc.2006.06.065. Epub 2006 Oct 17.


Objectives: Our prospective study tested the hypothesis that the 30-day clinical outcome of elective percutaneous catheter intervention (PCI) differs between strata defined by quartiles of platelet aggregation after loading with 600 mg clopidogrel.

Background: Platelet responses after loading with clopidogrel are highly variable. The impact of this variability on the peri-interventional risk of patients undergoing PCI has not been investigated prospectively.

Methods: Our study included 802 consecutive patients undergoing elective coronary stent placement. Before PCI, patients received a loading dose of 600 mg clopidogrel followed by 75 mg daily. Primary end point was the 30-day composite of death, myocardial infarction, and target lesion revascularization (major adverse cardiac events [MACE]). Platelet aggregation was assessed immediately before PCI by optical aggregometry (5 micromol/l adenosine diphosphate).

Results: During 30-day follow-up, 15 patients (1.9%) incurred MACE (3 deaths, 8 myocardial infarctions, 8 target lesion revascularizations). Quartiles of platelet aggregation were <4%, 4% to 14%, 15% to 32%, and >32%. Thirty-day MACE differed significantly (p = 0.034) between quartiles of platelet aggregation. It was 0.5% in the first quartile, 0.5% in the second, 3.1% in the third, and 3.5% in the fourth. Platelet aggregation above the median carried a 6.7-fold risk (95% confidence interval 1.52 to 29.41; p = 0.003) of 30-day MACE. Multivariable logistic regression analysis, including pertinent covariables, confirmed platelet aggregation as a significant independent predictor of 30-day MACE (adjusted odds ratio per 10% increase in platelet aggregation 1.32, 95% confidence interval 1.04 to 1.61; p = 0.026).

Conclusions: The level of platelet aggregation immediately before elective coronary stenting in patients pre-treated with a high loading dose of clopidogrel is correlated with early outcome after the procedure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angioplasty, Balloon, Coronary*
  • Cardiovascular Diseases / blood
  • Cardiovascular Diseases / drug therapy
  • Clopidogrel
  • Cohort Studies
  • Follow-Up Studies
  • Humans
  • Platelet Aggregation / drug effects
  • Platelet Aggregation / physiology
  • Platelet Aggregation Inhibitors / pharmacology
  • Platelet Aggregation Inhibitors / therapeutic use*
  • Prospective Studies
  • Stents*
  • Ticlopidine / analogs & derivatives*
  • Ticlopidine / pharmacology
  • Ticlopidine / therapeutic use
  • Treatment Outcome


  • Platelet Aggregation Inhibitors
  • Clopidogrel
  • Ticlopidine